Here is a suggestion for you. It is a gift for my dad's 50th birthday. On my dad's birthday, I bought two plane tickets to Hainan for my dad and mom, and I arranged everything for my parents, including accommodation. When my dad came back, he told me that this was the best birthday gift he had received in all these years, and it was also the most meaningful birthday gift.
There is another reason for giving you this suggestion. Your dad is 50 years old. People of his age are eager to go out more and see the beautiful mountains and rivers of the motherland when they are in good physical condition. What you did just met your dad's wish. Moreover, during the travel, dad can also gain some knowledge and relax the pressure in the city. Why not do it!
In addition, you can also give your dad some health food, or directly ask your parents to see what they are missing recently, or what they are interested in. In that case, the 50th birthday gift you gave to your dad can be sent to your dad's heart, and it will make your father happy!